Method of making composition cork



Patented Feb. 28, 1928.

UNITED STATES 1,660,529 PATENT OFFICE.

GEORGE SCHELLHAAS, OF NEW YORK, N. Y., ASSIGNOR TO THE CEM; SECURITIES COR- PORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Ho Drawing.

My invention relates to the method of making composition cork, and more part1cu larly to a method by which the setting of the adhesive or binder is accomplished without the application of heat to the compacted granular cork composition.

Heretofore it has been the common practiceinthe production of composition cork to form a mixture of granular cork and a fluid adhesive or binding medium, the proportions of which adhesive or binding medi-- um in relation to the cork, being such as to ensure 'the presence of a very thin film of the adhesive upon each cork granular. The adhesive coated cork isthen delivered to a mold and subjected to compression, the mold with its compressed contents being thereafter subjected to external heat for a time interval sufiicient to bring the adhesive or binder to a tacky condition and cause it to firmly bond adjacent granules of cork, and either partially or wholly set the adhesive or binder. Ordinarily the composition cork article after being withdrawn from the mold is permitted to season in an atmosphere at normal factory temperatures.

It has also been the practice to include in the adhesive or hinder, or to apply to the cork granules separately, glycerine or a glycerinesubstitute, the efiect of which is to prevent a tendency of the small particles of cork to hardenin a degree which will lessen the normal resiliency of the cork granules and consequently of the composition cork article in its entirety.

By methods heretobefore used, the subjection of the compacted cork to an elevated temperature applied externally of the mold for a prolonged period has a deteriorating action upon the cork so far as its resiliency is concerned, this in large measure, however, being counteracted by the glycerine or glycerine substitute. It has been found, however, that during the heating step, the glycerine or glycerine substitute, by capillary attraction, heat or otherwise, passes from the main body of the cork composition to adjacent the surface thereof contacting with the mold, so that the central port-ion of the article isdeprived in large measure of the beneficial action of the g1 cerine, except at and towards the surface 0 the article where there is an excess of glycerine.

With the above conditions in mind, I have provided armethod of making composition .after, it is essential that Application filed February 17, 1927. Serial No. 169,148.

cork, in which the application of heat to the compacted mass of cork composition and its binder is avoided, the setting of the binder not only occurring rapidly, but under normal temperatures.

While heretofore the methods of making composition cork have entailed the procedure of forming a batch of the cork long prior to the compaction of the batch in a mold, sometimes 12 to 24 hours, by the method of my invention the cork batch is made up and immediately delivered to with in the mold, thus not only shortening the time interval required by the method but making possible the setting of the binder without the application of external heat to the compacted cork composition.

In the practice of the method vention, as will more fully appear hereina self-setting binder, as distinguished from one requiring the application of heat thereto, be used, and that the binder include an agent which will temporarily retard the setting of the other ingredients thereof for a time interval merelysufiicient to batch.

The method of my invention has the further advantage that when the article is drawn from the mold, which is done when the mold'is at substantially factory temperatures, no further seasoning is required. With the method of my invention, the production of composition cork may be materially cheapened not only by reason of the shortening of the time required, but because of the possibility of using a very much smaller quantity of the adhesive, which is the most expensive ingredient entering into composition cork.

While to produce a highly resilient product, the use of heat is required, which heat is also required in the making of the hinder, the temperatures employed are sufliciently low to avoid any heat setting of the binder while it is being compounded. This heat, however, will have the effect of slightly ex-" panding the cork prior to and during compression so as to assist in securing a very close .grain in the finished product.

In the practice of the method of my invention, I use granular cork, the size of the granules of which may vary according to the nature of the article to be produced. If insulating material is to be made, large cork permit the compactionof the which it is ,ofthe weight of the cork granules may be used, but smaller granules are used when packing gaskets are to be made from the roduct, and if desired, granules of grade sizes may be admixed so as to prevent voids being resent in the product. Different grades 0 cork may also be used according to the use of articles to be made from the product.

The cork granules before admixture with the adhesive or binder as hereinafter referred to, are subjected to a drying temperature so as to remove from the cork as much of the moisture as is practicable.

The binder is then mixed, this binder consisting of an animal glue, including the albumens, in solution in water, the quantity of glue being from 5% to 10% by weight, of the batch, and the glue being in solution in 4 to 6 times its weight of water. To this mixture, glycerine or a glycerine substitute is added, the amount of the lycerine varying with difierent qualities 0% cork. For ordinary close grained composition cork, the glycerine content, with very satisfactory results, may range from 10% to 15% by weight of the other ingredients of the binder. These ingredients are mixed at a temperature below the setting point of the adhesive or binder, about 140 F. v

To this mixture is added a coagulating, or setting, agent acting upon the glue of the binder at normal temperatures, the uantity of this coagulant varying with ifierent glues and according to the rapidity with desired to handle the batch of cork composition. The coagulant ordinarily usedis formaldehyde, and excellent results can be secured wit from 3% to 5% of this constituent in the adhesive.

The tendency of formaldehyde is to almost instantly react with the glue, and hence it is essential to provide in the binder solution a retardant which will check the action of the coagulant for a suflicient time interval to emit the admixture of the adhesive or inder and the granular cork,

the delivery of the batch to the mold and the compaction of the mass before the adhesive or binder sets. The quantity and nature of this retardant is subject to wide variation according to the uses to which the composition cork articles are to be placed.

Various agents are known to manufacturers of glue for preventing the setting or hardening of the glue, including various acids such a salicylic, nitric, acetic, etc. Hydrochloric acid has a deleterious action on cork, and henee can not be used.

The retardant content in the solution will vary according to the time required to form the mixture and compact it in the mold. Ordinarily the quantity of this retardant in the solution Wlll range from 1% to 3%, but this maybe varied. It is desirable to proportion the retardant as closely as possible with relation to the time interval. required to form the batch and compress it in themold in order to shorten the final stage of the method.

- Under normal conditions, a batch of cork composition can be prepared and compacted in-the mold in from 2 to 3 minutes, it being desirable to add the coagulant and the retardant to the adhesive or binder just prior to the admixture of same with the granular cork, since this procedure will, with given proportions of the various ingrediehts of the binder, allow a greater time interval for the admixture of the binder and the cork and its compaction in the mold.

\Vhen the mold has been filled with com pacted cork composition it is allowed to stand for about an hour, during which period the adhesive will have set so that the cork article may be withdrawn from the mold at normal temperatures and be immediately ready for use.

No heat whatever is applied to the mold,

the only heat present being that of the adhesive or binder, and possibly of the cork composition, which as stated, is of a temperature which will not cause the coagulation or settin of the cement by heat. heat of the binder, however, will be transferred to the cork granules while within the mold, so as to cause a readjustment of the granules of cork with relation to each other as a result of the combined pressure fronr the compacting operation and from the heat expansion of these granules.

By the method of my invention the lycerine content of the binder is thoroughly distributed throughout the batch of cork composition so as to have a softening influence throu hout substantially the whole mam, and this glycerine is not disturbed through the final setting stage of the adhesive or binder. The result is a product in which the beneficial results of the glycerine are The substantially equally distributed throughout the article in its finished state.

In the production of composition cork articles in the manner herein described, I

am thus not only enabled to secure a more highly elastic product than by the heat curing methods heretofore practiced by reason of the retention of the glycerine or glycerine substitute distributed substantially equally throughout the mass, and avoid the actlon of the higher temperatures required by the heat setting process upon the cork itself, but the time required to produce the finished article, which article of'itself will have properties superior to the heat set product, is very materially reduced, which condition is accompanied by the usual manufacturing economies.

In the cork industry, the beneficial effects of glycerine have long been recognized, and

composition cork is itself an old product. The essential characteristics of the invention are therefore the utilization in such a product of a cold setting or curing stage made possible by the employment of a binder containing the coagulating or setting agent which reacts at normal temperatures to harden or set the glue of the binder, and the employment of a retardant which will check the reactions due to the presence of the coagulant for a sufficient interval to ermit the admixture of a batch of cork and inder and its delivery to, and compaction in, a-

mold, or its distribution and compaction'by other known methods.

The exact proportions of various ingredients herein stated are not fixed, but may be varied to meet desired manufacturing conditions.

lVhile I have herein referred to the use of granular cork, this term granular is intended to include cork particles of various sizes and shapes including what is known as cork wool which is shreds or chips of cork wood.

Having described the invention, what I claim as new and desire to have protected by Letters Patent, is

1. The herein described method of making composition cork embodying therein the formation of a batch of granular cork admixed with a fluid binder, containing glue, a coagulant for the glue, and a retardant for checking the reaction between the coagulant and the glue. subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

2. The herein described method of making composition cork embodying therein the formation of a batch of granular cork admixed with a fluid binder, containing glue, 2. coagulant for the glue, and a retardant for checking the reaction between the coagulant and the glue, said binder being at a temperature below that at which the glue will coagulate or set, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

3. The herein described method of making composition cork embodying therein the formation of a batch of granular cork from which moisture has been removed by a heat drying process, admixed with a fluid binder, containing glue, a coagulant for the glue, and a retardant for checking the reaction between the coagulant and the glue, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

4. The herein described method of making composition cork embodying therein the formation of a batch of granular cork from which moisture has been removed by a heat drying process, admixed with a fluid binder, containing glue, a coagulant for the glue, and a retardant for checking the reaction between the coagulant and the glue, said binder being at a temperature below that at which the glue will coagulate or set, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

5. The herein described method of making composition cork embodying therein the admixture with granular cork of a heated fluid binder containing. glue, adding a coagulant for the glue, and a retardant for checking the reaction between the coagulant and the.

glue immediately preceding the admixture of the binder with the cork, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

6. The herein described method of making composition cork embodying therein the admixture with granular cork of a heated fluid binder containing glue, adding a coagulant for the glue, and a retardant for checking the reaction between the coagulant and the glue immediately preceding the admixture of the binder with the cork, said binder being at a temperature below that at which the glue will coagulate or set, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing'the binder to set without the application of heat thereto.

7. The herein described method of making composition cork embodying therein the admixture with granular cork from which moisture has been removed by a'heat drying process, of a heated fluid binder containing glue, adding a coagulant for the glue, and a retardant for checking the reaction between the coagulant and the glue immediately preceding the admixture of the binder with the cork, said binder being at a temperature below that at which the glue will coagulate or set, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

8. The herein described method of mak- I ing composition cork embodying therein the formation of a batch of granular cork admixed with a fluid binder containing animal glue, and adding formaldehyde and an acid for checking the reaction between the formaldehyde and the glue immediately preceding the admixture of the binder and the cork, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

10. The herein described method of making composition cork embodying therein the formation of a batch of granular cork ad mixed with a fluid binder containing animal glue, and adding formaldehyde and an acid for checking the reaction between the formaldehyde and the glue immediately preceding the admixture of the binder and the cork, said binder being at a temperature below that at which the glue will coagulate or set, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

11. The herein described method of making composition cork embodying therein the formation of a batch of granular cork from which moisture has been removed by a heat drying process, admixed with a fluid binder, containin animal glue, formaldehyde, and an acid or checking the reaction between the formaldehyde and the glue, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

12. The here1n described method. of making composition cork embodying therein the formation of a batch of granular cork from which moisture has been removed by a heat drying process; admixed with a flui binder, containing animal glue, formaldehyde, and an acid for checking the reaction between the formaldehyde and the glue, said binder being at a temperature below that at which the glue will coagulate or set, subjecting the batch to pressure immediately following the mixture of the cork and the binder, and allowing the binder to set without the application of heat thereto.

In witness whereof I have hereunto aflixed my signature this 12th day of February, 1927.

GEORGE SCHELLHAAS. 

